Definition of Occupational asthma:

Occupational asthma is a lung disorder in which various substances found in the workplace lead to breathing difficulties.

See also:

• Bronchial asthma
• Pediatric asthma

Causes, incidence, and risk factors:

Many substances in the workplace can cause occupational asthma. The most common triggers are wood dust, grain dust, animal dander, fungi, or other chemicals (especially diisocyanates).

Though the actual rate of occurrence of occupational asthma is unknown, it is suspected to cause 2-20% of all cases of asthma in industrialized nations.

The following workers are at higher risk:

• Bakers
• Detergent manufacturers
• Drug manufacturers
• Farmers
• Grain elevator workers
• Laboratory workers
• Metal workers
• Millers
• Plastics workers
• Woodworkers

Symptoms:

Symptoms are usually due to airways inflammation and spasms of the muscles lining the airways, which cause the muscles to narrow excessively.

They usually occur shortly after being exposed to the offending substance and often improve or disappear when you leave work. Some people may not have symptoms until 12 or more hours after exposure to the allergen.

Symptoms usually get worse toward the end of the work week and may (but not always) go away on weekends or vacations.

In general, symptoms include:

• Coughing
• Tight feeling in the chest
• Shortness of breath
• Wheezing

Signs and tests:

The health care provider will perform a physical exam and ask questions about your medical history. There may be a pattern of worsening symptoms associated with a specific workplace environment or substance.

Wheezing may be heard when listening to the chest with a stethoscope.

The following tests may be used to diagnose this condition:

• Blood tests to detect specific antibodies to suspected offending substances
• Bronchial provocation test (test measuring reaction to the suspected allergen)
• Chest x-ray
• Complete blood count
• Peak expiratory flow rate
• Pulmonary function tests

Treatment:

The goal of treatment is to limit exposure to the asthma-causing substance and improve symptoms.

Treatment may include:

• Avoiding source of exposure
• Bronchodilators (inhalers or nebulizers)

Other therapies for asthma may be added in more severe cases.

In some instances, symptoms may persist despite removal of the source of exposure.

Support Groups:

See: Asthma and allergy - support group

Expectations (prognosis):

In general, the outcome for people with asthma is good. However, symptoms may persist for years after workplace exposure has been eliminated.

Complications:

• Respiratory fatigue
• Side effects of asthma medications

Calling your health care provider:

Call your health care provider if you have symptoms of asthma.

Prevention:

Asthma symptoms can be substantially reduced by avoiding known allergens and airway irritants.